How to measure a speed of an object efficiently and accurately is always a hot topic in the monitoring field. For example, when the object is a vehicle, monitoring the driving speed of the vehicle is of significant importance for avoiding traffic jam and planning route properly.
Currently, in a conventional method, the driving speed of the vehicle is monitored through an onboard Global Positioning System (GPS) apparatus. However, in this method, an additional GPS apparatus is required to be installed on the vehicle to be monitored. When communication with a satellite is failed due to failure in the GPS apparatus or driving in a tunnel or the like, the accuracy of this method will be affected largely.